### Wind [[Wave Formation]] requires a wind direction within approximately 30° of perpendicular to the mountain range, at speeds of at least 15-20kts. Vertical shear, or changes in wind velocity with altitude, will in part determine if waves will form as [[Trapped Lee Waves]] or [[Vertically Propagating Waves]]. ### Temperature [[Wave Formation]] requires atmospheric stability. The vertical temperature profile, or any changes in stability with altitude, will in part determine if waves will form as [[Trapped Lee Waves]] or [[Vertically Propagating Waves]]. ### Moisture [[Wave Formation]] is not contingent upon any specific moisture profile, however, increasing moisture will decrease atmospheric stability. The cloud forms present during wave conditions will be determined by the moisture content at varying levels. ### Terrain Generally, larger mountains with steeper slopes produce larger waves. Three-dimensional flow effects, such as uniformity or discontinuity to mountain peaks along a range, and flow around an individual mountain will influence the behavior of individual wave systems. Additionally, the downwind terrain can have constructive or destructive interference effects to the primary wave. ### Seasonal and Diurnal Effects Synoptic weather patterns favorable to wave conditions most frequently exist from late fall to early spring. Diurnal heating decreases stability and may inhibit wave formation, particularly at smaller mountain ranges in the warmer months.